1. Field of the Art
The present invention relates to an electrolytic titration apparatus and, more particularly, to an electrolytic cell for use in the apparatus.
2. State of the Art
It is well known that constituents produced in gas chromatography can be continuously measured in an electrolytic titration apparatus such as disclosed in U.S. Pat. No. 3,427,238 to Myers et al. Typically, such measurements must be made in about thirty seconds and must be precise to about 0.1 nanograms.
There are certain drawbacks with the Myers et al cell when it is operated in a mode to achieve the above mentioned titration time and sensitivity requirements. With the Myers et al cell, it is necessary to precisely adjust the cap which positions the sensor and working electrodes and to hold constant the gas input rate and the magnetic stir rate. Unfortunately, the electrolyte is evaporated from the cell during operation and a means for continuously replenishing the electrolyte in the Myers et al cell without lengthening the titration time and lessening the sensitivity has not been known.
Preventing the Myers et al and other titration cells in general from having easily achieved low titration times and sensitivity is the volume of electrolyte necessary for operation of the cells in question. Rapid titration times and greater sensitivities have been achieved by Myers and others by placing their sensor electrodes in close and precise proximity with the location at which the sample is introduced to the titration cell and attempting to average electrical noise caused by localized concentration effects. The noise has been reduced to a degree by use of rectangular electrode surfaces which add to cell size and by critical adjustment of the sensor electrode position.
These prior electrolytic cells, including the Myers et al cell, have not been capable of operation with cell electrolyte volumes of less than about five milliliters. The minimum size of the Myers et al cell, which is typical of prior art cells, is dictated by the presence of glass-to-metal seals for the electrodes to prevent contamination, square electrode surfaces and a stirring means such as a electrolyte stirring means.
The construction of prior electrolytic titration cells has also been complicated by the placement of fritted glass, fiber wick and other diffusion limiting means between the reaction chamber and a compartment in which the reference electrode is mounted.